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<head>
  <meta charset="UTF-8">
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  <meta name="viewport" content="width=device-width, initial-scale=1.0">
  <title>Document</title>
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<body>
  <script>
    const arr1=[1,2,3,4]
    const arr2=[2,2,2,3]
    // 1.
    const newArr1=[]
    for(let i =0;i<arr2.length;i++){
        if(arr1.indexOf(arr2[i]) !== -1 && newArr1.indexOf(arr2[i]) === -1) {
          newArr1.push(arr2[i])
        }
    }
    console.log(newArr1);

    //2.
    const newArr2 = arr1.filter(item =>{
      return arr2.includes(item)
    })
    console.log(newArr2);

  </script>
</body>
</html>